Function Of Redshift Research Articles

Compartmental description of the cosmological baryonic matter cycle

Context. The compartmental description, well-known as the description of infection diseases and epidemics, was applied here to describe the temporal evolution of the baryonic matter in interstellar gas and stars. The introduction of gaseous and stellar fractions of the total baryonic matter as the basic dynamical variables is advantageous because it allows us to apply the description to a variety of astrophysical systems. Aims. We aimed to theoretically investigate the competition of spontaneous star formation, stellar feedback, and stellar evolution to understand the baryonic matter cycle including luminous baryonic matter in main-sequence stars and weakly luminous matter in white dwarfs, neutron stars, and black holes (referred to as locked-in matter). Of particular interest was the understanding of cosmic star formation history and the present-day gas fraction with compartmental models. Methods. We derived exact analytical solutions for the time evolution of the fractions of gaseous, luminous stellar, and locked-in stellar matter for stationary rates of spontaneous star formation, continuous stellar feedback, and stellar evolution. The accuracy of the analytical solutions was proven by comparison with the exact numerical solutions of the dynamical equations. Results. The observed cosmological star formation rate and the integrated stellar density as a function of redshift are reasonably well explained by the compartmental model without triggered star formation by the competition of spontaneous star formation and stellar evolution, whereas the influence of stellar feedback is less important. The action of stellar evolution provides a significant redshift-dependent reduction factor when calculating the integrated stellar density from the star formation rate. Without stellar evolution, the observations could not be reproduced very well. Then, the fits to the observation provided conclusions on the relative importance of spontaneous star formation, stellar evolution, and feedback in the early Universe after the recombination era until today. The gas, luminous star, and locked-in stellar matter fractions indicated that the vast majority of the baryons in the present-day Universe reside in the form of locked-in stellar matter in white dwarfs, neutron stars, and black holes.

Imprints of the Einasto density profile and complexity factor on traversable wormholes in f(R, T) theory

The focus of this work is centered on determining whether traversable wormholes admitting Einasto density profile exist within the framework of f(R, T) gravity. Using the Morris–Thorne spacetime, we express the wormhole configuration and formulate the anisotropic gravitational equations for a particular linear modified model. Afterwards, by considering two different (constant and variable) redshift functions, we derive the shape function for wormholes and examine its potential stability. The developed functions conform to the necessary conditions and form a connection between two spacetime regions that are asymptotically flat. We also examine the viability of resulting wormhole solutions by verifying their violation with the null energy conditions. We also investigate the active gravitational mass and the complexity factor for our solutions. The later quantity is found to be negative near the wormhole throat and becomes zero when moving away from this point. Further, various methods of stability analysis are utilized to assess the developed models. Our results suggest that the constructed wormhole geometries meet the necessary conditions, thereby existing within the considered modified gravity.

Cosmography from accurate mass modeling of the lens group SDSS J0100+1818: Five sources at three different redshifts

Systems where multiple sources at different redshifts are strongly lensed by the same deflector allow one to directly investigate the evolution of the angular diameter distances as a function of redshift, and thus to learn about the geometry of the Universe. We present measurements of the values of the total matter density, $ m $, and of the dark energy equation of state parameter, $w$, through a detailed strong lensing analysis of SDSS J0100+1818, a group-scale system at $z=0.581$ with five lensed sources, from $z=1.698$ to $4.95$. We take advantage of new spectroscopic data from the Multi Unit Spectroscopic Explorer (MUSE) on the Very Large Telescope to securely measure the redshift of 65 sources, including the 5 multiply imaged background sources (lensed into a total of 18 multiple images) and 19 galaxies on the deflector plane, all employed to build robust strong lensing models with the software GLEE . The total mass distribution of the deflector is described in a relatively simple way, and includes an extended halo, the brightest group galaxy (BGG) with a measured stellar velocity dispersion of ($380.5 km.s^ $, and fainter members. We measure $ m $ in a flat Lambda cold dark matter (CDM) model, and $ m $ and $w = -1.27_ $ in a flat $w$CDM model. Given the presence of different sources angularly close in projection, we quantify through a multiplane approach their impact on the inferred values of the cosmological parameters. We obtain consistent median values, with uncertainties for only $ m $ increasing by approximately a factor of 1.5. Thanks to the remarkably wide radial interval where the multiple images are observed, ranging from 15 to 77 kpc from the BGG, we accurately measure the total mass profile and infer the stellar over total mass profile of the deflector. They result in a total mass of $(1.55 $ M$_ within 50 kpc and a stellar over total mass profile decreasing from <!PCT!>$ at the BGG effective radius to $(6.6 1.1) <!PCT!>$ at $R 77$ kpc. Our results confirm that SDSS J0100+1818 is one of the most massive (lens) galaxies known at intermediate redshift and one of the most distant candidate fossil systems. We also show that group-scale systems that act as lenses for $ 3$ background sources at different redshifts enable one to estimate the values of the cosmological parameters $ m $ and $w$ with an accuracy that is competitive with that obtained from lens galaxy clusters.

Role of the complexity factor and Karmarkar condition in constructing new wormhole models in dRGT gravity

This study delves into the distinctive characteristics of wormhole models in the context of de Rham-Gabadadze-Tolley (dRGT) massive gravity, providing insights into their theoretical behavior and stability. We use a null zero complexity factor to find the wormhole shape function for Model I. Additionally, we solve analytically the modified field equations describing wormhole for a given choice of logarithmic redshift function, exploiting the Karmarkar condition for embedding class one metrics for Model II. To achieve this, we analyze the wormhole geometry in a static spherical spacetime with an anisotropic matter configuration. The study investigates a number of parameters, including density, energy conditions, equation of state parameter, adiabatic sound velocity, and equilibrium condition. The solution shows a traversable wormhole that violates the null energy criterion and equilibrium state for certain ranges of free parameters. We employ adiabatic sound velocity analysis to concentrate on the stability of the wormhole. Furthermore, by using the equation of state parameter (ω), we conclude that both models end up in the phantom dark energy region. Finally, our findings highlight distinct photon deflection behaviors in dRTG massive gravity, with Model II showing negative angles indicative of repulsive gravity, while Model I exhibits positive angles, underscoring significant differences in gravitational dynamics.

X-ray AGN in Boötes: The lack of growth of the most massive black holes since z = 4

Abstract Supermassive Black Holes (BHs) are known to efficiently grow through gas accretion, but even sustained and intense mass build-up through this mechanism struggles to explain the assembly of the most massive BHs observed in the local Universe. Using the Chandra Deep-Wide Field Survey (CDFWS) in the Boötes field, we measure BH–galaxy assembly in massive galaxies ($M_\star \gtrsim 10^{10}\rm M_\odot$) through the AGN fraction and specific Black Hole accretion rate (sBHAR) distribution as a function of redshift and stellar mass. We determine stellar masses and star formation rates for a parent sample of optically selected galaxies as well as those with X-ray detections indicating the presence of an AGN through Spectral Energy Distribution (SED) fitting. We derive a redshift-dependent mass completeness limit and extract X-ray information for every galaxy as to provide a comprehensive picture of the AGN population in massive galaxies. While X-ray AGN samples are dominated by moderately massive host galaxies of $M_{\star } \geqslant 10^{10}\rm M_{\odot }$, we do not find a strong stellar mass dependence in AGN fraction (to limits in sBHAR), indicating a bias towards massive galaxies in the observed samples. We derive BH-galaxy growth tracks over time, which reveal that while most BH mass has been accumulated since z = 4 for lower mass BHs, the assembly of the most massive BHs is more complex, with little to no relative mass gain since z = 4, implying that rapid and intense growth episodes prior to z = 4 were necessary to form these massive BHs.

Confirming the evolution of the dust mass function in galaxies over the past 5 billion years

ABSTRACT The amount of evolution in the dust content of galaxies over the past 5 billion years of cosmic history is contested in the literature. Here, we present a far-infrared (FIR) census of dust based on a sample of 29 241 galaxies with redshifts ranging from $0 \lt z \lt 0.5$ using data from the Herschel Astrophysical Terahertz Large Area Survey ($H$-ATLAS). We use the spectral energy distribution fitting tool magphys and a stacking analysis to investigate the evolution of dust mass and temperature of FIR-selected galaxies as a function of both luminosity and redshift. At low redshifts, we find that the mass-weighted and luminosity-weighted dust temperatures from the stacking analysis both exhibit a trend for brighter galaxies to have warmer dust. In higher redshift bins, we see some evolution in both mass-weighted and luminosity-weighted dust temperatures with redshift, but the effect is strongest for luminosity-weighted temperature. The measure of dust content in galaxies at $z\lt 0.1$ (the dust mass function) has a different shape to that derived using optically selected galaxies from the same region of sky. We revise the local dust mass density ($z\lt 0.1$) to $\rho _{\rm d} =(1.37\pm 0.08)\times 10^5 {\rm \, {\rm M}_{\odot }\, Mpc^{-3}}\, h_{70}^{-1}$; corresponding to an overall fraction of baryons (by mass) stored in dust of $f_{\rm mb} {(\rm dust)} = (2.22\pm 0.13) \times 10^{-5}$. We confirm evolution in both the luminosity density and dust mass density over the past few billion years ($\rho _{\rm d} \propto (1+z)^{2.6 \pm 0.6}$), with a flatter evolution than observed in previous FIR-selected studies. We attribute the evolution in $\rho _{\rm L}$ and $\rho _{\rm m}$ to an evolution in the dust mass.

The importance of stochasticity in determining galaxy emissivities and UV LFs during cosmic dawn and reionization

The stochastic nature of star formation and photon propagation in high-redshift galaxies can result in sizable galaxy-to-galaxy scatter in their properties. Ignoring this scatter by assuming mean quantities can bias estimates of their emissivity and corresponding observables. We constructed a flexible, semi-empirical model, sampling scatter around the following mean relations: (i) the conditional halo mass function (CHMF); (ii) the stellar-to-halo mass relation (SHMR); (iii) the galaxy star formation main sequence (SFMS); (iv) the fundamental metallicity relation (FMR); (v) the conditional intrinsic luminosity; and (vi) the photon escape fraction. In our fiducial model, ignoring scatter in these galaxy properties overestimates the duration of the Epoch of Reionization (EoR), delaying its completion by $ z 1--2. We quantified the relative importance of each of the above sources of scatter in determining the ionizing, soft-band X-ray, and Lyman Werner (LW) emissivities as a function of scale and redshift. We find that scatter around the SFMS is important for all bands, especially at the highest redshifts where the emissivity is dominated by the faintest, most "bursty" galaxies. Ignoring this scatter would underestimate the mean emissivity and its standard deviation computed over 5 cMpc regions by factors of up to sim 2--10 at $5 z 15$. The scatter around the X-ray luminosity to star formation rate and metallicity relation is important for determining X-ray emissivity, accounting for roughly half of its mean and standard deviation. The importance of scatter in the ionizing escape fraction depends on its functional form, while scatter around the SHMR contributes at the level of sim 10--20<!PCT!>. Other sources of scatter have a negligible contribution to the emissivities. Although scatter does flatten the UV luminosity functions, shifting the bright end by 1--2 magnitudes, the level of scatter in our fiducial model is insufficient to fully explain recent estimates from JWST photometry (consistent with previous studies). We conclude that models of the EoR should account for the burstiness of star formation, while models for the cosmic 21cm signal should additionally account for scatter in intrinsic X-ray production.

Viable wormhole structures and energy conditions in f(Q, T) theory

Abstract This paper explores static wormhole solutions in f(Q, T) theory, where Q is the non-metricity and T is the trace of energy-momentum tensor. We derive the field equations that describe gravitational phenomena in the existence of non-metricity and matter source terms We examine different models of this theory to determine the explicit expressions of matter contents, which are useful for analyzing the wormhole structures. We investigate the existence of feasible traversable wormhole solutions for constant and variable redshift functions. To determine whether physically viable wormhole geometry exists, we examine the graphical interpretation of energy constraints for different values of model parameters. It is found that realistic traversable and stable wormhole solutions exist only for the first model of this gravity.

Conservative wormholes in generalized [formula omitted]- function

We present an exhaustive study of wormhole configurations in κ(R,T) gravity with linear and non-linear functions. The model assumed Morrison-Thorne spacetime where the redshift and shape functions linked with the matter contain and geometry of the spacetime through non-covariant conservation equation of the stress-energy tensor. The first solution was explored assuming a constant redshift function that leads to a wormhole (WH) which is asymptotically non-flat. The remaining solutions were explored in two cases. Firstly, assuming a linear equation of state p(r)=ωρ(r) along with different forms of κ(R,T)-function. This proved enough to derive a shape function of the form b(r)=r0(r0r)1/ω. Secondly, by assuming specific choices of the shape function consistent with the wormhole configuration requirements. All the solutions fulfill flare-out condition, asymptotically flat and supported by phantom energy. Further, the embedding surface and its revolution has been generated using numerical method to see how the length of the throat is affected of the coupling parameters through κ(R,T) function. At the end, we have also calculated the average null energy condition, which is satisfied by all the WH models signifying minimum exotic matter is required to open the WH throats.

Accelerated Structure Formation: The Early Emergence of Massive Galaxies and Clusters of Galaxies

Galaxies in the early Universe appear to have grown too big too fast, assembling into massive, monolithic objects more rapidly than anticipated in the hierarchical Lambda cold dark matter (ΛCDM) structure formation paradigm. The available photometric data are consistent with there being a population of massive galaxies that form early (z ≳ 10) and quench rapidly over a short (≲1 Gyr) timescale, consistent with the traditional picture for the evolution of giant elliptical galaxies. Similarly, kinematic observations as a function of redshift show that massive spirals and their scaling relations were in place at early times. Explaining the early emergence of massive galaxies requires either an extremely efficient conversion of baryons into stars at z > 10 or a more rapid assembly of baryons than anticipated in ΛCDM. The latter possibility was explicitly predicted in advance by modified Newtonian dynamics (MOND). We discuss some further predictions of MOND, such as the early emergence of clusters of galaxies and early reionization.

Deflection of light by wormholes and its shadow due to dark matter within modified symmetric teleparallel gravity formalism

Abstract We explore the possibility of traversable wormhole formation in the dark matter halos in the context of f(Q) gravity. We obtain the exact wormhole solutions with anisotropic matter source based on the Bose–Einstein condensate, Navarro-Frenk-White, and pseudo-isothermal matter density profiles. Notably, we present a novel wormhole solution supported by these dark matters using the expressions for the density profile and rotational velocity along with the modified field equations to calculate the redshift and shape functions of the wormholes. With a particular set of parameters, we demonstrate that our proposed wormhole solutions fulfill the flare-out condition against an asymptotic background. Additionally, we examine the energy conditions (ECs), focusing on the null ECs at the wormhole’s throat, providing a graphical representation of the feasible and negative regions. Our study also examines the wormhole’s shadow in the presence of various dark matter models, revealing that higher central densities result in a shadow closer to the throat, whereas lower values have the opposite effect. Moreover, we explore the deflection of light when it encounters these wormholes, particularly noting that light deflection approaches infinity at the throat, where the gravitational field is extremely strong.

A Simple Model of the Radio–Infrared Correlation Depending on Gas Surface Density and Redshift

We introduce a simple parametric model of the radio–infrared correlation (i.e., the ratio between the IR luminosity and the 1.4 GHz radio luminosity, q IR) by considering the energy loss rate of high-energy cosmic-ray (CR) electrons governed by radiative cooling (synchrotron, bremsstrahlung, inverse Compton scattering), ionization, and adiabatic expansion. Each process of CR electron energy loss is explicitly computed and compared to each other. We rewrite the energy loss rate of each process to be dependent on the gas surface density and redshift using the relevant scaling relations. By combining each energy loss rate, the fraction of the synchrotron energy loss rate is computed as a function of gas surface density and redshift and used to extrapolate the well-established “local” radio–infrared correlation to the high-redshift Universe. The locally established q IR is reformulated to be dependent upon the redshift and the gas surface density and applied for understanding the observed distribution of the radio–infrared correlation of high-redshift galaxies in I. Delvecchio et al. Our model predicts that the q IR value is anticorrelated with gas surface density and the redshift dependency of the q IR value changes by the gas surface density of galaxies, which captures the observed trend of q IR values for stellar-mass-selected star-forming galaxies with a minimal impact of radio–infrared selection bias.

The role of stellar mass in the cosmic history of star formation as seen by Herschel and ALMA

Aims . We explore the contribution of galaxies, as a function of their stellar mass, to the cosmic star formation history (CSFH). In order to avoid uncertain extrapolations of the infrared luminosity function, which is often polluted by the contribution of starbursts, we base our analysis on stellar mass. Attenuation by dust is accounted for thanks to the combination of deep surveys by Herschel and the Atacama Large Millimeter/submillimeter array (ALMA). Methods. We combined for the first time the deepest Herschel (GOODS-South, GOODS-North, COSMOS and UDS) and ALMA (GOODS-South) surveys. We constrained the star formation rate (SFR), dust mass ($M_ dust $), dust temperature ($T_ dust $) and gas mass ($M_ gas $) of galaxies as a function of their stellar mass ($M_ star $) from $z to $z by performing a stacking analysis of over 128,000 Hubble Space Telescope (HST) H -band selected galaxies. We studied the evolution of the star formation efficiency of galaxies as a function of redshift and $M_ star Results . We show that the addition of ALMA to Herschel allows us to reach lower $M_ star $ and higher redshifts. We confirm that the SFR-$M_ star $ star formation main sequence (MS) follows a linear evolution with a slope close to unity with a bending at the high-mass end at $z<2$. The mean $T_ dust $ of MS galaxies evolves linearly with redshift, with no apparent correlation with $M_ star $. We show that, up to $z massive galaxies (i.e. star M_ odot $) account for most of the total SFR density ($ SFR $), while the contribution of lower-mass galaxies (i.e. $M_ star M_ odot $) is rather constant. We compare the evolution of star-forming galaxy (SFGs) to the cosmological simulation TNG100. We find that TNG100 exhibits a noticeable difference in the evolution of the CSFH, that is, the marked evolution of massive galaxies found in the observations appears to be smoothed in the simulation, possibly due to feedback that is too efficient. In this mass complete analysis, $H$-dropout (also called HST-dark) galaxies account for $ 23<!PCT!>$ of the CSFH in massive galaxies at $z$$>$3. Finally, we find hints that the star formation efficiency of distant galaxies ($z$=3--5) is stronger (shorter depletion time) as compared to low-redshift galaxies.

Type Ia Supernovae from First-generation Stars

Type Ia supernovae (SNe Ia) discovered at redshift z ≲ 2.5 are presumed to be produced from Population I/II stars. In this work, we investigate the production of SNe Ia from Population III binaries in the cosmological framework. We derive the SN Ia rate as a function of redshift in a theoretical context for the production of first-generation stars and evaluate the likelihood of their detection by the James Webb Space Telescope (JWST). Assuming the initial stellar mass function (IMF) favors low-mass stars, as from recent numerical simulations, we found that Population III stars may give rise to a considerable number of SNe Ia at high redshift, and Population III stars may even be the dominant SN Ia producer at z ≳ 6. In an optimistic scenario, we expect ∼1(2) SNe Ia from Population III stars at z ≈ 4(5) for a survey of area 300arcmin2 during a 3 yr period with JWST. The same survey may record more than ∼400 SNe Ia at lower redshift (z ≲ 2.5) but with only about one of them from Population III progenitors. There will be ∼six Population III SNe Ia in the same field of view at redshifts of 5–10. Observational constraints on SN Ia rates at the redshift range of 5–10 can place crucial constraints on the IMF of Population III stars.

Constraining the Initial Mass Function via Stellar Transients

The stellar initial mass function (IMF) represents a fundamental quantity in astrophysics and cosmology describing the mass distribution of stars from low mass all the way up to massive and very massive stars. It is intimately linked to a wide variety of topics, including stellar and binary evolution, galaxy evolution, chemical enrichment, and cosmological reionization. Nonetheless, the IMF still remains highly uncertain. In this work, we aim to determine the IMF with a novel approach based on the observed rates of transients of stellar origin. We parametrize the IMF with a simple but flexible Larson shape, and insert it into a parametric model for the cosmic UV luminosity density, local stellar mass density, type Ia supernova (SN Ia), core-collapse supernova (CCSN), and long gamma-ray burst (LGRB) rates as a function of redshift. We constrain our free parameters by matching the model predictions to a set of empirical determinations for the corresponding quantities via a Bayesian Markov Chain Monte Carlo method. Remarkably, we are able to provide an independent IMF determination with a characteristic mass mc=0.10−0.08+0.24M⊙ and high-mass slope ξ=−2.53−0.27+0.24 that are in accordance with the widely used IMF parameterizations (e.g., Salpeter, Kroupa, Chabrier). Moreover, the adoption of an up-to-date recipe for the cosmic metallicity evolution allows us to constrain the maximum metallicity of LGRB progenitors to Zmax=0.12−0.05+0.29Z⊙. We also find which progenitor fraction actually leads to SN Ia or LGRB emission (e.g., due to binary interaction or jet-launching conditions), put constraints on the CCSN and LGRB progenitor mass ranges, and test the IMF universality. These results show the potential of this kind of approach for studying the IMF, its putative evolution with the galactic environment and cosmic history, and the properties of SN Ia, CCSN, and LGRB progenitors, especially considering the wealth of data incoming in the future.

Dispersion and rotation measures from fast radio burst (FRB) host galaxies based on the TNG50 simulation

Context. Fast radio bursts (FRBs) are poised to become important cosmological tools in the near future, as the number of observed FRBs is increasing rapidly with multiple surveys underway. A large sample of FRBs will soon have available dispersion measures (DMs) and rotation measures (RMs), which can be used to study the cosmic baryon density and the intergalactic magnetic field. However, the observed DM and RM of FRBs consists of multiple contributions that must be quantified to estimate the DM and RM of the intergalactic medium (IGM). Aims. In this paper, we estimate one such contribution to DM and RM, namely, of FRB host galaxies. We show how this contribution changes with redshift, galaxy type, and the stellar mass of the galaxies. We also investigate its dependence on galaxy inclination and on an FRB’s offset from the center of the galaxy. Methods. Using the TNG50 simulation of the IllustrisTNG project, we selected 16 500 galaxies at redshifts of 0≤ ɀ ≤2, with stellar masses in the range of 9 ≤ log(M*/M⊙) ≤ 12. In each galaxy, we calculated the DM and RM contributions of 1000 sightlines; from these, we constructed the DM and RM probability density functions (PDFs). Results. We find that the rest frame DM distributions of all galaxies at a given redshift can be fitted by a log normal function and its median and width increase as a function of redshift. The rest-frame RM distribution is symmetric, with a median RMhost,rf=0 rad m–2 and it can be fitted by a combination of a Lorentzian and two Gaussian functions. The redshift evolution of the distribution width can be fitted by a curved power law. The parameters of these functions change for different subsets of galaxies with different stellar mass, inclination, and FRB offset. These changes are due to an increasing ne with redshift, SFR, and stellar mass. We do find a more ordered B field at lower ɀ compared to higher ɀ, as suggested by the presence of more galaxies with B field reversals and B fields dominated by random B field at higher ɀ. Conclusions. We estimated the FRB host DM and RM contributions, which can be used in the future to isolate the IGM contribution from the observed DM and RM of FRBs. We predict that to constrain a σRM,IGM of 2 rad m–2 to the 95% confidence level, we would need to observe 95 000 FRBs at ɀ = 0.5, but only 9 500 FRBs at ɀ = 2.

The GLASS-JWST Early Release Science Program

We release fully reduced spectra obtained with NIRSpec onboard JWST as part of the GLASS-JWST Early Release Science Program and a follow-up Director’s Discretionary Time program 2756. From these 263 spectra of 245 unique sources, acquired with low (R = 30–300) and high dispersion (R ~ 2700) gratings, we derive redshifts for 200 unique sources in the redshift range ɀ = 0–10. We describe the sample selection and characterize its high completeness as a function of redshift and apparent magnitude. Comparison with independent estimates based on different methods and instruments shows that the redshifts are accurate, with 80% differing less than 0.005. We stack the GLASS-JWST spectra to produce the first high-resolution (R ~ 2700) JWST spectral template extending in the rest frame wavelength from 2000 Å to 20 000 Å. Catalogs, reduced spectra, and template are made publicly available to the community.

Physical characteristics of anisotropic solutions in f(Q,T) gravity under the vanishing complexity, embedding class one, conformally flat and conformally Killing conditions

The foundation of this paper is to present a comparative study of the properties of anisotropic solutions for compact stars in the framework of modified f(Q,T) gravity for the first time under the schemes of vanishing complexity, embedding class one, conformally flat and conformally Killing, where Q is the nonmetricity scalar and T is the trace of the energy-momentum tensor. The model f(Q,T)=ϕQ+αQn+1−γ(1−e−Q/γ)+βT is chosen in order to compare the results of the various forms f(Q,T) and f(Q) gravity theories. The f(Q,T) and f(Q) gravities in this model are then further simplified to depend on parameters ϕ,α,γ&β. Then, we discussed several approaches to determining the spherically symmetric spacetime components. Schwarzschild geometry represents the exterior spacetime, while a Tolman-Kuchowiz spacetime is used to examine the spherically symmetric spacetime inside the interior geometry. Many properties of compact stars are investigated, like energy density, energy conditions, pressure profiles, sound speeds, gradients, adiabatic index, TOV equation, mass function, compactness, and redshift function are all carefully examined in order to complete the analysis. We have compiled results for both stable and unstable scenarios, derived from gravity theories categorized into various cases, with solutions considered under different frameworks such as Tolman-Kuchowiz spacetime, embedding class 1 spacetime, the vanishing complexity condition, the conformally flat condition, and the conformal Killing vector condition.

The PAU Survey: The quasar and UV luminosity functions at 2.7<z<5.3

We present the Lyman-alpha ( and ultraviolet (UV) luminosity function (LF) in bins of redshift for quasars selected in the Physics of the Accelerating Universe Survey (PAUS). A sample of 915 objects was selected at $2.7<z<5.3$ within an effective area of $ 36$ deg$^2$ observed in 40 narrow-band (NB) filters (FWHM $ We cover the intermediate--bright luminosity regime of the LF erg\,s $; $-29<M_ UV <-24$). The continuous wavelength coverage of the PAUS NB set allows very efficient target identification and precise redshift measurements. We show that our method is able to retrieve a relatively complete ($C 85<!PCT!>$) and pure ($P 90<!PCT!>$) sample of quasars for $ $. In order to obtain corrections for the LF estimation, and assess the accuracy of our selection method, we produced mock catalogs of $0<z<4.3$ quasars and galaxies that mimic our target population and their main contaminants. Our results show a clear evolution of the and UV LFs, with a declining tendency in the number density of quasars toward increasing redshifts. In addition, the faint-end power-law slope of the LF becomes steeper with redshift, suggesting that the number density of quasars declines faster than that of fainter emitters. By integrating the LF, we find that the total emitted by bright quasars per unit volume rapidly declines with increasing redshift, being subdominant to that of star-forming galaxies by several orders of magnitude by $z 4$. Finally, we stack the NB pseudo-spectra of a visually selected ``golden sample'' of 591 quasars to obtain photometric composite SEDs in bins of redshift, enabling us to measure the mean intergalactic medium absorption using the Lyman-alpha forest as a function of redshift, yielding results consistent with previous spectroscopic determinations.

Constraining the parameters of generalized and viscous modified Chaplygin gas and black hole accretion in Einstein-Aether gravity

In this paper, we investigate the phenomenon of the accelerated cosmic expansion in the late universe and the mass accretion process for a four-dimensional Einstein-Aether black hole. Starting with the basics of Einstein-Aether gravity theory, we first consider the field equations and two well-known models of Chaplygin gas, i.e., the generalized cosmic Chaplygin gas model and viscous modified Chaplygin gas model. We then obtain the energy density and Hubble parameter equations for these models in terms of various dimensionless density parameters and some unknown parameters. After finding the required parameters, we proceed with the mass accretion process. For both models, we obtain the equation of mass in terms of the redshift function and graphically represent the change in the mass of the black hole with a redshift. At the same time, we perform a graphical comparison between these models and the Λ\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$\\Lambda $$\\end{document}CDM model of the universe. Finally, we conclude that the mass of a four-dimensional black hole will increase along the evolution of the universe within the framework of Einstein-Aether gravity.